Updated ecommerce payment settings to simplify sandbox configuration
Updated ecommerce payment settings to simplify sandbox configuration

Additional variables have been exposed to simplify automated configuration of payment processors on sandboxes.

LEARNER-1474

stvstnfrd/configuration,appsembler/configuration,EDUlib/configuration,gsehub/configuration,gsehub/configuration,gsehub/configuration,edx/configuration,hks-epod/configuration,appsembler/configuration,hastexo/edx-configuration,hastexo/edx-configuration,appsembler/configuration,stvstnfrd/configuration,edx/configuration,Stanford-Online/configuration,arbrandes/edx-configuration,hks-epod/configuration,stvstnfrd/configuration,michaelsteiner19/open-edx-configuration,arbrandes/edx-configuration,EDUlib/configuration,rue89-tech/configuration,proversity-org/configuration,edx/configuration,Stanford-Online/configuration,hastexo/edx-configuration,mitodl/configuration,rue89-tech/configuration,arbrandes/edx-configuration,edx/configuration,proversity-org/configuration,stvstnfrd/configuration,gsehub/configuration,mitodl/configuration,hks-epod/configuration,mitodl/configuration,proversity-org/configuration,proversity-org/configuration,michaelsteiner19/open-edx-configuration,michaelsteiner19/open-edx-configuration,hks-epod/configuration,hks-epod/configuration,EDUlib/configuration,Stanford-Online/configuration,Stanford-Online/configuration,arbrandes/edx-configuration,EDUlib/configuration,gsehub/configuration,hastexo/edx-configuration,arbrandes/edx-configuration,hastexo/edx-configuration,rue89-tech/configuration,rue89-tech/configuration,rue89-tech/configuration,proversity-org/configuration,EDUlib/configuration,mitodl/configuration,Stanford-Online/configuration,stvstnfrd/configuration,appsembler/configuration,michaelsteiner19/open-edx-configuration